toDataURL() is now synchronous, and works with all nodes, including the stage, layers, groups, and shapes. This also sets things up nicely for node caching. You can now cache anything, including the whole stage, layers, groups, or shapes, manifested as Kinetic Images that were instantiated with data urls

dist/kinetic-core.js

@@ -288,9 +288,9 @@ Kinetic.Type = {
             var context = canvas.getContext('2d');
             context.putImageData(arg, 0, 0);
             var dataUrl = canvas.toDataURL();
-			var imageObj = new Image();
-			imageObj.src = dataUrl;
-			return imageObj;
+            var imageObj = new Image();
+            imageObj.src = dataUrl;
+            return imageObj;
         }
 
         // default
@@ -1284,6 +1284,31 @@ Kinetic.Node = Kinetic.Class.extend({
     getImageData: function() {
         return this.imageData;
     },
+    /**
+     * Creates a composite data URL. If MIME type is not
+     * specified, then "image/png" will result. For "image/jpeg", specify a quality
+     * level as quality (range 0.0 - 1.0)
+     * @name toDataURL
+     * @methodOf Kinetic.Stage.prototype
+     * @param {String} [mimeType]
+     * @param {Number} [quality]
+     */
+    toDataURL: function(mimeType, quality) {
+        var bufferLayer = this.getStage().bufferLayer;
+        var bufferCanvas = bufferLayer.getCanvas();
+        var bufferContext = bufferLayer.getContext();
+        bufferLayer.clear();
+        this._draw(bufferLayer);
+
+        try {
+            // If this call fails (due to browser bug, like in Firefox 3.6),
+            // then revert to previous no-parameter image/png behavior
+            return bufferLayer.getCanvas().toDataURL(mimeType, quality);
+        }
+        catch(e) {
+            return bufferLayer.getCanvas().toDataURL();
+        }
+    },
     _setImageData: function(imageData) {
         if(imageData && imageData.data) {
             this.imageData = imageData;
@@ -1836,7 +1861,7 @@ Kinetic.Container = Kinetic.Node.extend({
             var child = children[n];
             if(child.nodeType === 'Shape') {
                 if(child.isVisible() && stage.isVisible()) {
-                    child._draw(layer ? layer : child.getLayer());
+                    child._draw( layer ? layer : child.getLayer());
                 }
             }
             else {
@@ -1995,48 +2020,6 @@ Kinetic.Stage = Kinetic.Container.extend({
             layers[n].clear();
         }
     },
-    /**
-     * Creates a composite data URL and passes it to a callback. If MIME type is not
-     * specified, then "image/png" will result. For "image/jpeg", specify a quality
-     * level as quality (range 0.0 - 1.0)
-     * @name toDataURL
-     * @methodOf Kinetic.Stage.prototype
-     * @param {function} callback
-     * @param {String} mimeType (optional)
-     * @param {Number} quality (optional)
-     */
-    toDataURL: function(callback, mimeType, quality) {
-        var bufferLayer = this.bufferLayer;
-        var bufferContext = bufferLayer.getContext();
-        var layers = this.children;
-        var that = this;
-
-        function addLayer(n) {
-            var dataURL = layers[n].getCanvas().toDataURL();
-            var imageObj = new Image();
-            imageObj.onload = function() {
-                bufferContext.drawImage(this, 0, 0);
-                n++;
-                if(n < layers.length) {
-                    addLayer(n);
-                }
-                else {
-                    try {
-                        // If this call fails (due to browser bug, like in Firefox 3.6),
-                        // then revert to previous no-parameter image/png behavior
-                        callback(bufferLayer.getCanvas().toDataURL(mimeType, quality));
-                    }
-                    catch(exception) {
-                        callback(bufferLayer.getCanvas().toDataURL());
-                    }
-                }
-            };
-            imageObj.src = dataURL;
-        }
-
-        bufferLayer.clear();
-        addLayer(0);
-    },
     /**
      * serialize stage and children as a JSON object
      * @name toJSON
@@ -2190,6 +2173,51 @@ Kinetic.Stage = Kinetic.Container.extend({
     getDOM: function() {
         return this.content;
     },
+    /**
+     * Creates a composite data URL. If MIME type is not
+     * specified, then "image/png" will result. For "image/jpeg", specify a quality
+     * level as quality (range 0.0 - 1.0).  Note that this method works
+     * differently from toDataURL() for other nodes because it generates an absolute dataURL
+     * based on what's draw onto the canvases for each layer, rather than drawing
+     * the current state of each node
+     * @name toDataURL
+     * @methodOf Kinetic.Stage.prototype
+     * @param {String} [mimeType]
+     * @param {Number} [quality]
+     */
+    toDataURL: function(mimeType, quality) {
+        var bufferLayer = this.bufferLayer;
+        var bufferCanvas = bufferLayer.getCanvas();
+        var bufferContext = bufferLayer.getContext();
+        var layers = this.children;
+        bufferLayer.clear();
+        
+        for(var n = 0; n < layers.length; n++) {
+            var layer = layers[n];
+            var layerUrl;
+            try {
+                // If this call fails (due to browser bug, like in Firefox 3.6),
+                // then revert to previous no-parameter image/png behavior
+                layerUrl = layer.getCanvas().toDataURL(mimeType, quality);
+            }
+            catch(e) {
+                layerUrl = layer.getCanvas().toDataURL();
+            }
+
+            var imageObj = new Image();
+            imageObj.src = layerUrl;
+            bufferContext.drawImage(imageObj, 0, 0);
+        }
+
+        try {
+            // If this call fails (due to browser bug, like in Firefox 3.6),
+            // then revert to previous no-parameter image/png behavior
+            return bufferLayer.getCanvas().toDataURL(mimeType, quality);
+        }
+        catch(e) {
+            return bufferLayer.getCanvas().toDataURL();
+        }
+    },
     _resizeDOM: function() {
         var width = this.attrs.width;
         var height = this.attrs.height;
@@ -3014,6 +3042,28 @@ Kinetic.Layer = Kinetic.Container.extend({
     getContext: function() {
         return this.context;
     },
+    /**
+     * Creates a composite data URL. If MIME type is not
+     * specified, then "image/png" will result. For "image/jpeg", specify a quality
+     * level as quality (range 0.0 - 1.0).  Note that this method works
+     * differently from toDataURL() for other nodes because it generates an absolute dataURL
+     * based on what's draw on the layer, rather than drawing
+     * the current state of each child node
+     * @name toDataURL
+     * @methodOf Kinetic.Stage.prototype
+     * @param {String} [mimeType]
+     * @param {Number} [quality]
+     */
+    toDataURL: function(mimeType, quality) {
+        try {
+            // If this call fails (due to browser bug, like in Firefox 3.6),
+            // then revert to previous no-parameter image/png behavior
+            return this.getCanvas().toDataURL(mimeType, quality);
+        }
+        catch(e) {
+            return this.getCanvas().toDataURL();
+        }
+    },
     /**
      * private draw children
      */
@@ -3028,7 +3078,8 @@ Kinetic.Layer = Kinetic.Container.extend({
         }
 
         if(this.attrs.clearBeforeDraw) {
-            this.clear();
+            var clearLayer = layer ? layer : this;
+            clearLayer.clear();
         }
 
         if(this.isVisible()) {